Over the past years, High Dynamic Range (or HDR) displays have become more and more popular during the international electronics exhibitions. They offer a new user experience as they can show images and videos with high brightness (until 4000 nits) compared to standard or Standard Dynamic Range (SDR) displays (150-400 nits). HDR devices are able to display videos with more details in black levels and with a higher global contrast. Despite the growth of HDR video content, there is a need to display existing standard videos on HDR displays. For this purpose, inverse tone mapping operators (ITMO) have been developed for converting video from Standard Dynamic Range (SDR) to High Dynamic Range (HDR) avoiding banding issues when luminance is extended. ITMO could be used either as a plugin within a post-production tool to help colorist for manual grading, or as hardware within a System On Chip (Soc) for set-top box or TV set. In the latter case, SDR-HDR conversion is achieved on the fly.
Despite the above-mentioned advantages of the HDR displays, it has been commonly noticed that viewers can be blinded by pictures presenting high peak of brightness especially inside dark rooms. Therefore, viewers are distracted by some parts of bright image breaking the immersion from the movie action, even dazzled when watching a sequence of explosion scenes.
More specifically, HDR video sequences presenting transitions from dark to bright sequences generate a series of flash that cause eye strain for the viewers. This discomfort is much higher as the frequency of alternating dark to bright scene is higher. This is often the case in action movies. This effect is not visible in the SDR version because the brightness of each video shot of the sequence is manually adjusted during the color grading operation in order to ensure maximum visual comfort for the viewer. But this problem is not taken into account in the existent SDR to HDR conversion (or inverse tone mapping) process.